Businesses in diverse fields such as insurance, medicine and law require the storage and retrieval of a large number of documents. A useful storage system must provide an efficient, safe, and low cost method of preserving a large number of documents. At the same time, a good storage system should provide a quick and easy method of retrieving stored documents. The availability of computer systems and scanners that can quickly convert a paper document into an electronic data file has allowed the development electronic storage systems where documents are stored as files on permanent storage media in a computer system.
In the past, electronic storage systems have used WORM (write once optical disk) or Read-Write optical disks for archiving files because of their durability and storage capacity. Since WORM and Read-Write optical disks can be written much like a hard disk, document image files are simply written to the optical disk as they become available. Optical disks readers are expensive, however, and electronic storage systems usually use a juke box device to load optical disks into a small number of optical readers. Juke box devices degrade the storage system's performance because they are slow and unreliable and because they must physically manipulate an optical disk to insert it into a reader.
CD-ROM systems are also used for storing documents. CD-ROM readers are relatively cheap allowing an electronic storage system to have many readers. Thus, CD-ROM systems have an advantage over WORM and Read-Write systems because CD-ROM systems are not slowed down by a juke box device to load disks. However, unlike WORM and Read-Write optical disks, all the documents necessary to fill a 650 MB CD need to be published in one write operation. A CD-ROM can hold about 15000 document image files. These files are temporarily saved on storage devices like a computer hard disk. When enough files have accumulated on the hard disk to fill a CD-ROM, they are downloaded to a CD-ROM publisher or transferred to tape to be sent to an outside publisher. The user is responsible for determining when enough files are present to fill a CD-ROM and for initiating the writing of these files.
The CD-ROM publishing process is not instantaneous and the CD-ROM corresponding to the downloaded files may not be available for days or weeks. If a user wants continuous access to the image files, there is a period of time before the CD-ROM is published where the downloaded files must be maintained on the temporary storage device. The user is responsible for maintaining coherent file storage for these downloaded files. When the CD-ROM is published and installed in the system, the user is must update the location of all the transferred files to indicate their presence on that CD-ROM. Keeping track of the location and status of such a large number of files is a formidable and time consuming task.